How to diagnose no fuel in the injector rail on a 97 TJ 4.0


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Hello,
my Jeep sat for about 16 years with no attendance what so ever. Last week I bought a new battery, checked the spark plugs and the cabels. Spark plugs are recieving power so the problem is not the ignitionn system. I wanted to empty the tank but it was empty, I remember filling it up last time to the brim, so it evaporoted in 15 years. I filled it now with 20 Liters of fuel. I tried to start it starter works, engin turns but it wont start. I check the valve at the fuel rail no fuel comes out. I also dont heare the pump priming. I need to get the jeep running because towing it in Austria is so expensive 600-1000 euros thats alot. Does any one know what I can do to resolve this problem.

Best regards Lennart from Austria not Australia
 

glowell222

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Hello, and welcome to the forum.

The fuel line runs from the tank to the intake manifold along the left-side frame rail (if you are in the Jeep looking forward). It is metal for some of the distance, and rubber at the tank and at the fuel rail. I would check that this is intact the entire length, with no bends, breaks, kinks. After this, check all of the fuses. Next, there is a fuel relay in the power distribution unit under the hood-large black covered box on the same side as the battery. There is a diagram inside the lid of the box that details the location of the relay. You can swap this relay for one of the others in the PDU, turn on the key and wait 5 seconds, then check to see if you are getting fuel at the rail. I recommend turning the key on, waiting 5 seconds, turn it off, repeat 3 times before checking the rail. If you are still not getting fuel at the rail, you are going to have to drop the fuel tank to get at the pump/sender unit.
 

TJ4Jim

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Hello,
my Jeep sat for about 16 years with no attendance what so ever. Last week I bought a new battery, checked the spark plugs and the cabels. Spark plugs are recieving power so the problem is not the ignitionn system. I wanted to empty the tank but it was empty, I remember filling it up last time to the brim, so it evaporoted in 15 years. I filled it now with 20 Liters of fuel. I tried to start it starter works, engin turns but it wont start. I check the valve at the fuel rail no fuel comes out. I also dont heare the pump priming. I need to get the jeep running because towing it in Austria is so expensive 600-1000 euros thats alot. Does any one know what I can do to resolve this problem.

Best regards Lennart from Austria not Australia
At this point your options are down to removing the tank, pump assembly, fuel line, fuel rail and injectors so everything can be flushed out and clean. beyond that there are no quick fixes for a gummed up fuel system.
 
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LennartfromAustria
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How did it all go? You get it up and running?
Hello, and welcome to the forum.

The fuel line runs from the tank to the intake manifold along the left-side frame rail (if you are in the Jeep looking forward). It is metal for some of the distance, and rubber at the tank and at the fuel rail. I would check that this is intact the entire length, with no bends, breaks, kinks. After this, check all of the fuses. Next, there is a fuel relay in the power distribution unit under the hood-large black covered box on the same side as the battery. There is a diagram inside the lid of the box that details the location of the relay. You can swap this relay for one of the others in the PDU, turn on the key and wait 5 seconds, then check to see if you are getting fuel at the rail. I recommend turning the key on, waiting 5 seconds, turn it off, repeat 3 times before checking the rail. If you are still not getting fuel at the rail, you are going to have to drop the fuel tank to get at the pump/sender unit.
I tried what you recomended but still no fuel... My Vather left the Jeep for 10 Years in a Garge without any attention. So propably the pump is dead. And I found that I have a rear main seal leak... My Jeep has 32.000 Miles... Yikes
 
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LennartfromAustria
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At this point your options are down to removing the tank, pump assembly, fuel line, fuel rail and injectors so everything can be flushed out and clean. beyond that there are no quick fixes for a gummed up fuel system.
Thats going too be a nice project:cautious:... Wanted to install a lift kit and so on :)
 
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LennartfromAustria
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X2, the old fuel probably turned to gum/varnish. It won't be easy cleaning the fuel system.
Hello Jerry,
Greetings, I think I am going to buy a new fuel pump assembly. Could you recommend a assembly maybe bosh, delfi or a different one. And I have another question about the rear main seal leak on my 4.0/ax15 what do I have to remove to get access to the seal? And could you recommend a seal too, that would be very helpful!

Best regards Lennart
 

Jerry Bransford

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Hello Jerry,
Greetings, I think I am going to buy a new fuel pump assembly. Could you recommend a assembly maybe bosh, delfi or a different one. And I have another question about the rear main seal leak on my 4.0/ax15 what do I have to remove to get access to the seal? And could you recommend a seal too, that would be very helpful!

Best regards Lennart
Hello Lennart, hello from the US! :) Unfortunately Bosch no longer makes the entire fuel pump assembly for 2004 and older Wranglers, just the fuel pump itself. For the entire assembly I'd probably go with a Dephi. Make sure to avoid AIrtex or Spectre.

For you rear main seal, try this first... change your engine oil to a CONVENTIONAL high-mileage engine oil. The rear main seal quite often develops leaks from using some synthetic engine oils which can let the rear main seal dry out and shrink. High mileage versions of conventional engine oils contain extra amounts of seal conditioners that can restore the rear main seal to its original size and stop it from leaking. I had a BMW that had a bad rear main seal leak and switching to a high mileage conventional engine oil completely stopped the leak within 4-5 days.
 
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LennartfromAustria
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Hello Lennart, hello from the US! :) Unfortunately Bosch no longer makes the entire fuel pump assembly for 2004 and older Wranglers, just the fuel pump itself. For the entire assembly I'd probably go with a Dephi. Make sure to avoid AIrtex or Spectre.

For you rear main seal, try this first... change your engine oil to a CONVENTIONAL high-mileage engine oil. The rear main seal quite often develops leaks from using some synthetic engine oils which can let the rear main seal dry out and shrink. High mileage versions of conventional engine oils contain extra amounts of seal conditioners that can restore the rear main seal to its original size and stop it from leaking. I had a BMW that had a bad rear main seal leak and switching to a high mileage conventional engine oil completely stopped the leak within 4-5 days.
Thanks Jerry, I will try a conventional high/mileage engine oil. If it doesn't work, what do I have to remove to get too the seal? I read something about removing the starter, Exhaust, Transmission Inspection cover and the engine mount. Is that right or is there a simpler way?

Best greetings Lennart
 

Jerry Bransford

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Thanks Jerry, I will try a conventional high/mileage engine oil. If it doesn't work, what do I have to remove to get too the seal? I read something about removing the starter, Exhaust, Transmission Inspection cover and the engine mount. Is that right or is there a simpler way?
I have high expectations of the high mileage conventional engine oil fixing the leak. But if it does not, you have to remove the engine pan and exhaust to get to the seal.

Give the high mileage conventional engine oil some time to work, I suspect you will be happy with the results.
 
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LennartfromAustria
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I have high expectations of the high mileage conventional engine oil fixing the leak. But if it does not, you have to remove the engine pan and exhaust to get to the seal.

Give the high mileage conventional engine oil some time to work, I suspect you will be happy with the results.
Thanks again Jerry, I have one additional question about my fuel issue. There is no fuel in the rail when I tried to start it. How can I diagnose the issue step by step.


Best regards Lennart
 

Wtrask

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You can get a fuel pressure gauge fairly cheap. My Jeep sat for a few years like yours and 3 of my 6 injectors started leaking. It would crank over for a bit and then run really rich because of all the fuel that leaked into the cylinders. I also had to replace my fuel pump because the regulator was bad. If I were you attach a fuel gauge to the Schraeder valve on the fuel rail then turn the key to on and listen for the pump to come on. I would do it a couple of times. Then watch the gauge and see how fast the psi goes down. If it’s very fast it’s probably a regulator. Otherwise could be injectors. The easiest way is to pull the rail out and prime the fuel system and look for injector leaks.
 

TJ4Jim

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Thanks again Jerry, I have one additional question about my fuel issue. There is no fuel in the rail when I tried to start it. How can I diagnose the issue step by step.


Best regards Lennart
For a simple test to visually confirm fuel flow you can disconnect the fuel line from the rail (need a disconnect tool at the rail connection) and stick the tank end in a large soda bottle and turn the key to the run position without cranking the starter. If the system still does not flow then do the same test at the rear connection from the hard line to the fuel pump hose.

All of this is assuming you can hear the pump go thru the priming mode for about 2 seconds when the key is turned to the run position.
 
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LennartfromAustria
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You can get a fuel pressure gauge fairly cheap. My Jeep sat for a few years like yours and 3 of my 6 injectors started leaking. It would crank over for a bit and then run really rich because of all the fuel that leaked into the cylinders. I also had to replace my fuel pump because the regulator was bad. If I were you attach a fuel gauge to the Schraeder valve on the fuel rail then turn the key to on and listen for the pump to come on. I would do it a couple of times. Then watch the gauge and see how fast the psi goes down. If it’s very fast it’s probably a regulator. Otherwise could be injectors. The easiest way is to pull the rail out and prime the fuel system and look for injector leaks.
Do I tested the Schraeder Valve, but not fuel not a single drop. And I don't hear the pump priming
 
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LennartfromAustria
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For a simple test to visually confirm fuel flow you can disconnect the fuel line from the rail (need a disconnect tool at the rail connection) and stick the tank end in a large soda bottle and turn the key to the run position without cranking the starter. If the system still does not flow then do the same test at the rear connection from the hard line to the fuel pump hose.

All of this is assuming you can hear the pump go thru the priming mode for about 2 seconds when the key is turned to the run position.
I don't hear the pump prime
 
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LennartfromAustria
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I have high expectations of the high mileage conventional engine oil fixing the leak. But if it does not, you have to remove the engine pan and exhaust to get to the seal.

Give the high mileage conventional engine oil some time to work, I suspect you will be happy with the results.
Do you know what that spot on the fuel tank could be?

IMG_20200613_160808.jpg
 

Wtrask

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Looks like your gonna need to pull the pump. Make sure you check all your fuses first just in case it’s that simple.
 

TJ4Jim

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I don't hear the pump prime
There is a fuel pump wire connector just forward of the tank on the drivers side, you can pull the connector apart and test for a momentary 12V source while you have someone turn the key.

The pump can be hard to hear, typically there will be a humming noise that lasts for about 2 seconds before shutting off.
 
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